Chapter 15.28
HILLSIDE DEVELOPMENT
Sections:
15.28.030 Development standards generally.
15.28.050 Soils, grading and drainage.
15.28.060 Driveways and streets.
15.28.010 Purpose.
The purpose of this chapter is to encourage the orderly development of hillside areas by relating the number and distribution of dwelling units and other buildings to the topography, so the terrain will suffer minimum disfigurement by scarring from extensive cut and fill. These regulations are also designed to minimize danger to life and property due to the hazards of fire, flood soil erosion, seepage, and destruction of natural topography and plant material. (Ord. 894 § 1, 1990)
15.28.020 Hillside defined.
“Hillside” means areas which in general have a median slope before grading of more than fifteen (15) percent on fifty (50) percent or more of the site. Less steep slopes which strongly relate to areas of greater slope may also be included within hillside areas. (Ord. 894 § 2, 1990)
15.28.030 Development standards generally.
Prior to any development on a hillside, a development plan shall be submitted to the planning commission for approval. The planning commission shall consider such plan at a public hearing duly advertised by state law. The decision of the planning commission is final, unless an appeal is made to the city council within fifteen (15) days of the action of the planning commission.
The development shall substantially conform to the standards set out in the following sections. (Ord. 894 § 3 (part), 1990)
15.28.040 Lot design.
Minimum lot sizes shall be based on the grade of slope prior to grading in the following manner: A. In the 15 - 30% grade classification, 70% of the lots shall have 10,000 sq. ft. with the overall average of 10,000 sq. ft.
|
Minimum Lot Size |
Grade of Slope |
|---|---|
|
7,200 sq. ft. net |
0 - 15% |
|
10,000 sq. ft. net |
15 - 30% |
|
20,000 sq. ft. gross |
31- 40% |
|
40,000 sq. ft. gross |
Greater than 40% |
B. In the 30% - 40% grade classification, 70% of the lots shall have a minimum of 20,000 sq. ft. with the overall average of 20,000 sq. ft.
C. In the 40% grade classification, 70% of the lots shall be 40,000 sq. ft. or more with the average of all lots a minimum of 40,000 sq. ft.
D. In all cases, where deviation from the minimum lot size are permitted, no lot shall be less than 7,200 sq. ft.
E. Grade of Slope Map. In order to determine the areas to which the various grade of slope classification, apply, the applicant shall submit a grade of slope calculating the change in elevation or natural grade per one hundred (100) feet of horizontal distance. The contours of the map shall be in five (5) feet increments.
For purposes of calculating median slope the following formula shall be used:
S = 0.002296xIxL A
|
Where: |
||
|
S |
= |
average natural slope in percent |
|
I |
= |
natural contour interval in feet |
|
L |
= |
length of natural contours in feet |
|
A |
= |
acres of property |
|
0.002296 |
= |
constant which converts square feet into acres and expresses slope in percent. |
F. Minimum Parcel Dimensions. In order to comply with the minimum lot area required by these regulations, there are no absolute parcel widths and depths. Buildable area is considered to be contiguous area of the lot which is less than thirty (30) percent of slope.
G. Setbacks. Front, side, and rear set backs shall be determined based on the precise development plan and consideration of the constraints.
H. Building Height. Dwelling and other accessory structures shall not exceed thirty-five (35) feet in overall height as measured from the median grade across the buildable area.
I. Parking. Parking shall be as noted in the zoning ordinance.
J. Building Pads. The maximum building pad for each parcel shall be as follows:
|
Slope |
Pad Standards |
|---|---|
|
0-15% |
100% of lot may be graded pad |
|
15-30% |
60% of lot may be graded |
|
31-40% |
35% of lot may be graded |
|
40% or greater |
20% of lot may be graded |
K. Building Design. Buildings shall normally be designed to have sliding glass doors and open recreational areas facing the downhill side of the lot in order to take advantage of the views. (Ord. 894 § 3(A), 1990)
15.28.050 Soils, grading and drainage.
The general grading guidelines for a hillside development are as follows:
A. Slopes. Cut and fill slopes shall generally not exceed thirty (30) feet in height, unless otherwise approved by Planning Commission. The cut or fill slope shall generally be located on the downhill adjacent property.
B. Retaining Walls. Retaining walls shall not exceed six feet in height except in front yards areas where they shall not exceed thirty-six (36) inches in height. However, retaining walls necessary for the construction of an adjacent driveway may be constructed to a maximum of six feet in height anywhere on the property.
3. Drainage and Erosion. All graded areas shall be protected from wind and water erosion through acceptable slope stabilization methods such as planting, walls or netting.
On-site catch basins or siltation basins, as well as energy absorbing devices may be required as a means to prevent erosion as well as to provide for groundwater recharge.
Natural drainage courses should generally be protected from grading activity.
Where brow ditches are required, naturalize with plant material and native rock.
The outside corners or edges of all cut and fill slopes, except at the tops of slopes shall be required to be rounded to eliminate the sharp corners and shall have a minimum curvature of radius of at least five feet.
Landforming shall be applied to all slopes adjacent to public streets, gateways and public view areas, as well as all slopes greater than one hundred (100) feet in length or ten feet in vertical height.
1. Landforming shall be accomplished by the use of variable slope ratios, undulating the tops and toes, screening of terraces and down drains, varying of surface features, and by landscaping.
2. Rear and side yard slopes between adjacent lots within the same project need not landformed unless they are greater than one hundred (100) feet in length or ten feet in vertical height. (Ord. 894 § 3(B), 1990)
15.28.060 Driveways and streets.
Driveways and streets should be designed in such a way as to avoid excessive cut and fill slopes. As a general rule excessive shall be interpreted to be slopes greater than thirty (30) feet in vertical height.
A. Gradient and Driveway Width Adjacent to Garage Entrance. Driveways shall have a maximum gradient of twelve (12) percent along the center line of that portion of the driveway located within twenty (20) feet of the garage entry. The width of the driveway shall not be less than the width of the garage opening(s) within twenty (20) feet of the drywall entrance.
B. Gradient and Driveway Width of Remainder of Driveways. The maximum gradient for driveways farther than twenty (20) feet of the opening shall be twenty (20) percent along its centerline and shall not be less than twelve (12) feet in width.
C. Vertical Transition. Any vertical transitions shall be so designed and constructed so that any portion of a vehicle with a twelve (12) feet wheel base and five inches under vehicle clearance will not make contact with the driveway surface.
D. Street Grades. Street grades shall not normally exceed fifteen (15) percent in grade.
E. Street Improvements. All street improvements shall be to city standards except as allowed by these regulations.
1. Widths. In order to minimize grading, where lot sizes average greater than ten thousand (10,000) square feet, street right of way may be reduced to forty (40) feet, with thirty-two (32) feet of curb to curb width.
2. Curb, Gutter and Sidewalk. Where hydrology permits, curb in the hillside area may be of the “roll curb” type. Sidewalk is not required within the forty (40) feet right-of-way area.
3. In the forty (40) feet right-of-way, parking shall be permitted on one side only if standard curb and gutter is constructed and on both sides when “roll curb” is used. (Ord. 894 § 3(C), 1990)
15.28.070 Infrastructure.
All lots on the hillside shall be connected to a public sewer system. All lots on a hillside shall be serviced by underground utilities. Water mains shall be of an appropriate size to provide the minimum fire protection required by the city. (Ord. 894 § 3(D), 1990)
15.28.080 Landscaping.
As a condition to the final approval of a hillside development plan and prior to the recordation of any map or issuance of a building permit, whichever occurs first, landscaping plans, including planting design and irrigation system, all of which are prepared by a licensed landscape architect, shall be submitted and approved by the planning commission.
All cut, fill, and natural slopes, not specifically designated as permanent open space shall be planted with deeply rooted plants or other plants approved by the city, which are able to acclimate to the environment. Intermediate stabilization will be required while deeply rooted are developing.
The planning commission shall consider the following in reviewing, the landscape plans. The planting of slopes for stabilization, the fire resistance ability, durability, size and quality of the plant material, and planting design. Proof of the ability of the soil to sustain the plant material may also be required.
Slope planting and irrigation systems shall be provided by the applicant on all slopes of three or more feet in vertical height. The subject cut and fill slopes shall be adequately planted with landscaping consisting of approximately one-third shrubs and trees, and the remaining two-thirds grass or ground cover and/or trees and shrubs. (Ord. 894 § 3(E), 1990)
15.28.090 Irrigation.
All systems and planting shall be complete and operative on an individual lot basis before final approval of finished grade and before occupancy of any buildings.
Maintenance of required landscaping is the responsibility of the landowner(s). A landscape maintenance bond for a minimum of one year’s duration from the date of acceptance of landscaping shall be required to guarantee that all plants shall be maintained and replaced as necessary, until the property is permanently occupied. (Ord. 894 § 3(F), 1990)
15.28.100 Fire protection.
A. In fire hazard areas, unobstructed fire protection equipment access easements shall be required to all parts of the development and to adjacent area, which are potential fire hazards. The fire chief shall recommend to the planning commission the necessary locations of such easements.
Additionally, the fire department may require fuel modification zones to minimize the fire threats to private property.
B. Any construction within two hundred (200) feet of a fire hazard area, including stairs, balconies, porches, and open structure under buildings, which are not of noncombustible materials shall be protected by one-hour construction.
All eaves shall be fully boxed in with exterior stucco or its equivalent fire resistive construction. Any required vents shall be covered with one-fourth inch mesh or its equivalent.
All roof coverings within two hundred (200) feet of fire hazard area shall be rated as Class A in accordance with the Uniform Building Code Standards. (Ord. 894 § 3(G), 1990)